The crew will grow to five next week. In August, a Russian Progress completed a record rapid rendezvous of less than four hours.
Feustel, who served as Expedition 56 commander, and Arnold, who served as flight engineer, participated in dozens of educational downlink events while in space, reaching hundreds of thousands of students.
'They affirmed the necessity of further close interaction between NASA and Roscosmos technical teams in identifying and eliminating the cause of the leak, as well as continuation of normal ISS operations and NASA's ongoing support of the Roscosmos-led Soyuz investigation.
Arnold has spent more than 209 days in space during the course of two missions.
Feustel and Arnold were also able to escape the confines of the space station.
United States astronaut Richard Arnold, left, Russian cosmonaut Oleg Artemyev, center, and USA astronaut Andrew Feustel sit shortly after the landing of the Russian Soyuz MS-08 space capsule about 150 km (80 miles) south-east of the Kazakh town of Dzhezkazgan, Kazakhstan, Octovber 4, 2018.
Mr Artemyev conducted one spacewalk together with a fellow Russian.
The hole has been identified and fixed by space station crew.
Sputnik's launch isn't the only reason why October 4 is a red-letter day in space history: Today also marks the 14th anniversary of the SpaceShipOne flight that won the $10 million Ansari X Prize for private-sector spaceflight.
Back on the space station, Alexander Gerst of the European Space Agency is now in command.
NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin are scheduled to launch Thursday, Oct. 11 for a same-day arrival, adding to the crew of Expedition 57.
Since the retirement of NASA's space shuttle in 2011, Russia's Soyuz has offered the only ride for people to and from the station.